Fergie wrote: “The hardest part of Roy's body is his tongue. He has the most savage tongue you can imagine. He can debilitate the most confident person in the world in seconds with that tongue.

“What I noticed about him that day when I was arguing with him was that his eyes started to narrow, almost to wee black beads. It was frightening to watch. And I'm from Glasgow."

(Photo: Getty)

Keane admits he has learned lessons from his spells as manager of Sunderland and Ipswich.

Keane believes his time at the two clubs has been judged unfairly, although he concedes there were plenty of things he would do differently.

He said: “Where do you want to start? We could be here all day.

“The area where I certainly need to improve, and every club manager would say the same, is recruitment.”

But he is disappointed not to have been offered another chance since leaving Portman Road in 2011.

He maintained: “I have no problems with clubs not giving me an opportunity but I would say that some clubs should certainly have spoken to me over the last year or two.

“I felt clubs should have given me another opportunity to get back into football. Not every job, don’t get me wrong, I’m not waiting for the phone to ring.

“But there’s a few clubs I’ve looked at and went ‘I think that would suit me, that would suit my personality’.

“I think I did OK at Sunderland. Even at Ipswich we did OK. But that’s for another day. It’s a long story.”

Keane insists his desire to succeed is as strong as ever but denied he would walk out on Ireland if a leading club knocked on his door.

“I don’t think that will happen,” he said. “You have to live in the now instead of worrying about what might happen.

“You could be sitting at home for the next year or two waiting for the opportunity but the opportunity has come to work with Martin O’Neill and I feel very lucky.”

"Stick it up your b******s!" How it all went wrong with Ireland

1991

Keane was not impressed with the Irish set-up from his first taste as an Under-21 against Turkey, later calling it “a bit of a joke”.

He ran into a row with boss Jack Charlton by making himself unavailable for a trip to Algeria despite Charlton warning him he would never play for Ireland again if he failed to show up.

1994

After dismissing Charlton’s style of play, he was selected for the World Cup in the USA, and the Irish shocked Italy 1-0 in the group stages. They returned as heroes after a second-round exit to Holland, but Keane said: “There was nothing to celebrate. We achieved little.”

2002

Keane played superbly to help Ireland qualify for the 2002 World Cup in Japan and South Korea, but, once there, the problems began.

The FAI selected a training facility in Saipan, which Keane detested, expressing grave doubts about the quality of the set-up and of the squad’s preparations. His mood was not improved by the late arrival of training equipment and he said the pitch was “like a car park”.

A row ensued with keepers coach Pat Bonner and teammate Alan Kelly, after which Keane announced he was flying home. He had to wait an extra night for a flight during which boss Mick McCarthy persuaded him to stay, though Colin Healy was already called up.

But Keane gave an interview to Tom Humphries, of The Irish Times, slamming the set-up and preparations again, leading McCarthy to confront him in front of the squad.

Keane then delivered his personal opinion of McCarthy: “Mick, you’re a liar, you’re a f***ing w***er. I didn’t rate you as a player, I don’t rate you as a manager, and I don’t rate you as a person. You’re a f***ing w***er and you can stick your World Cup up your a***. The only reason I have any dealings with you is that somehow you are the manager of my country! You can stick it up your b*****ks.”

Keane flew home and unwound by walking his beloved dog Triggs.

2004

Keane recalled by new boss Brian Kerr, but quit after failure to reach the 2006 World Cup.